Long‐term population isolation in the endangered tropical tree species Caesalpinia echinata Lam. revealed by chloroplast microsatellites

Abstract

Habitat fragmentation represents the single most serious threat to the survival of tropical ecosystems. In formulating strategies to counteract the detrimental effects of fragmentation, knowledge of the levels and patterns of genetic diversity within and between natural populations is vital to the establishment of any conservation programme. We utilized polymorphic chloroplast microsatellite markers to analyse genetic diversity in populations of the endangered tropical tree Caesalpinia echinata Lam. representing the entire extant range of the species. Levels of within-population diversity were low, with only two of seven populations studied displaying any variation. The vast majority of the genetic variation was partitioned between geographical regions (36%) and between populations within regions (55%). These levels of genetic structuring, coupled with a calculated pollen-to-seed flow ratio of approximately 6.7:1, suggest that there has been little gene flow between the three major geographical regions over an extended period. Thus, the current tripartite distribution of the species is more consistent with the existence of separate glacial refugia, rather than reflecting any anthropogenic effects.

Genetic resource impacts of habitat loss and degradation; reconciling empirical evidence and predicted theory for neotropical trees

“…For biodiversity, the single most important impact of these activities is loss of primary habitat (Lira et al, 2003). However, the degradation of habitat also leaves a lasting legacy with which biota must cope if they are to continue to survive.…”

“…Quantifying the impact of habitat degradation on remnant forest stands will not only help assess genetic and some ecological consequences of these changes but will also help to (1) ascertain the conservation value of remnant stands, (2) estimate future repercussions of tropical deforestation, and (3) formulate strategies for effective conservation and sustainable management of the genetic resources for species inhabiting degraded landscapes White et al, 1999;Lemes et al, 2003;Lira et al, 2003).…”

“…Keywords: fragmentation; gene flow; genetic diversity; inbreeding; neotropical trees; selective logging Introduction Anthropogenic destruction of tropical forests has dramatically increased in recent decades, and the threat to tropical ecosystems is well articulated (eg Bawa and Seidler, 1998;White et al, 1999;Trejo and Dirzo, 2000;Ghazoul and McLeish, 2001). For biodiversity, the single most important impact of these activities is loss of primary habitat (Lira et al, 2003). However, the degradation of habitat also leaves a lasting legacy with which biota must cope if they are to continue to survive.…”

Genetic consequences of subtropical rainforest fragmentation onMacadamia tetraphylla(Proteaceae)

“…Empirical studies examining the genetic impacts of habitat fragmentation have demonstrated that the process can bring about a variety of gene-flow alterations. Frequently, plant populations experience increased levels of inbreeding and random genetic drift following fragmentation (YOUNG et al, 1996;DAYANANDAN et al, 1999;COLLEVATTI et al, 2001;LIRA et al, 2003;CARDOSO et al, 2005;LOWE et al, 2005). The magnitude of such gene flow alterations depends on the severity and duration of the reduction in population size (BARRET and KOHN, 1991).…”

Variations in sugars and cyclitols during development and maturation of seeds of brazilwood (Caesalpinia echinata Lam., Leguminosae)

“…(brazilwood, pernambuco-wood) is a tree species native to the Brazilian Atlantic coast and occurs mainly in areas of dry seasonal forests (Lira et al, 2003). It is an endangered species (Ibama, 1992), having been used as dyestuff in the past and currently it is still utilized for the manufacturing of high-quality bows of string instruments (Lewis, 2001;Rocha, 2004).…”